1. Field of the Invention
This invention relates to mitigating or reducing skin irritation in allergic contact dermatitis.
Contact dermatitis manifests itself in an inflammation of the skin. In mild cases the symptoms are itching, burning or reddening of the skin. In more severe cases vesiculation and edema may be present and may be followed by weeping and crusting. The most severe cases may be accompanied by bleeding vesicles and gross edema.
Contact dermatitis can be classified as allergic contact dermatitis or as primary irritant dermatitis. Although the symptoms of both types of dermatitis are similar there are some basic differences which are widely recognized.
Primary irritant dermatitis is the more common form of contact dermatitis and is caused by irritating agents which will cause dermatitis in all persons upon sufficient exposure. The period between contact with the primary irritant and the onset of symptoms is short or absent.
Allergic contact dermatitis may be caused by many substances which contact the skin. However, in this type of dermatitis a given substance may cause a dermatological reaction in certain subjects only. This reaction usually does not occur with the initial contact, but only upon subsequent exposures. Moreover, the reaction occurs only in these now "sensitized" subjects and there is a time interval between contact and development of symptoms. Sensitization is caused by previous contact to the irritating substance. Some persons never become sensitized, others require numerous contacts and some require only a few contacts for sensitization. Thus, an essential difference is recognized between allergic contact dermatitis and primary irritant dermatitis, the latter being predictably induced by substances irritating to all persons the former being erratically induced, if at all, and only after sensitization.
Among the most common naturally occuring allergens capable of sensitizing and causing allergic contact dermatitis in a large proportion of subjects are the antigenic plants of the genus Rhus, such as poison ivy, poison oak, and poison sumac. The symptoms of reddening of the skin, formation of an itchy rash and often blistering of the skin common to all types of contact dermatitis are particularly familiar to many as a result of contact with poison ivy or other plants of the genus Rhus. Such dermatologic reactions are extremely irritating and in severe cases can cause temporary incapacitation of an individual. With the advent of the greater use of the outdoors by people, such as is experienced in camping, hiking, nature study and similar activities, especially in wooded or relatively less populated areas, the probability of contact with skin irritating plants is increased and therefore the need for protection against irritation resulting therefrom becomes apparent.
While allergic contact dermatitis due to poison ivy, poison oak, poison sumac and like antigenic plants is widely known it is equally well established that allergic contact dermatitis is caused by a large number of materials encountered by workers in industry. Such materials may be end products, raw materials, intermediates and by products of industrial processes. The problem of occupational allergic contact dermatitis is a significant one resulting in lost man hours of production, lost wages, discomfort to workers, job changes and workmen's compensation payments. Examples of materials known to cause allergic contact dermatitis among industrial and non-industrial workers are dinitrochlorobenzene, insecticides containing pyrethrum or Rotenone, dye intermediates such as aniline, nitro compounds, anthracene and derivatives thereof, benzidine and its compounds, naphthylamines and benzanthrone and its compounds, dyes such as paraphenylenediamine, aniline black, paramido phenol, amido-azo-toluene, amido-azo-benzene, Malachite Green, Metanil Yellow, Nigrosine and Rosaniline, photo developers such as hydroquinone, para-amido-phenol and pyrogallol, rubber accelerators and antioxidants such as hexamethylene tetramine, tetramethyl thiuram monosulfide, paratoluidine, phenyl beta naphthylamine and triethyl trimethyl triamine, coal tar and its derivatives such as pyridine and phenanthrene, explosives such as trinitrotoluol, tetranitro-methyl aniline, ammonium nitrate and sodium nitrate and synthetic and natural resins such as wood rosin and phenol formaldehyde.
2. Description of the Prior Art
It is khown that protection against skin irritation can be achieved in subjects sensitized to allergens such as plants of the genus Rhus by exposing the subject to a controlled series of contacts with the allergenic irritant. The concentration of allergen, usually in an innocuous vehicle, in each subsequent controlled exposure can be increased so as to buildup a degree of immunity to the allergenic substance. Such a procedure results in temporary or partial protection against skin irritation caused by contact with the specific allergen or closely related allergens. However, the procedure, carried out under a physician's direction is somewhat tedious, inconvenient and often uncomfortable. Alternatively, the application of heretofor known lotions, creams and balms etc. to the skin prior to or even after contact with the skin irritant affords an ineffective method of preventing or reducing skin irritation due to many materials encountered by workers in industry and plants of the genus Rhus, such as poison ivy, poison oak and poison sumac.
It is also known that the degree of skin irritation caused by certain primary irritants, particularly organic detergents, can be prevented or reduced by incorporating agents called "mildness additives" by Kelly and Ritter in U.S. Pat. No. 3,630,934, issued Dec. 28, 1972, and in U.S. Pat. No. 3,538,009, issued Nov. 3, 1970. However, the Kelly and Ritter patents relate to reduction of the irritation from primary irritants and not to reduction of irritation from agents which cause allergic contact dermatitis following sensitization.
Accordingly, it was surprising to discover that certain compounds including the mildness agents mentioned in the Kelly Ritter patents mentioned above would also reduce skin irritation due to allergic contact dermatitis following contact of a sensitized subject with allergens such as found in industry and genus Rhus plants.